Exhaust nozzle assembly

Abstract

An exhaust nozzle assembly for a gas turbine engine. The assembly includes concentrically arranged inner mixer and outer exhaust nozzles, the exhaust nozzle extending axially downstream of said mixer nozzle. A centre-body is axially mounted within and extends axially downstream from the mixer nozzle. A core flow duct is defined by the mixer nozzle and the centre-body, the core flow duct having a core exit area. An exhaust duct is defined at least in part by the exhaust nozzle downstream of the mixer nozzle, the exhaust duct having an exhaust exit area. The mixer nozzle includes a mixer cowl which is axially-translatable along the centre axis and the exhaust nozzle includes an exhaust cowl which is either axially-translatable along or angularly-adjustable relative to the centre axis. The assembly further includes an actuation mechanism and the mixer cowl and exhaust cowl are movable by the actuation mechanism.

We claim: 
     
       1. An exhaust nozzle assembly for a gas turbine engine having a centre axis, said assembly comprising:
 a concentrically arranged inner mixer nozzle and outer exhaust nozzle, the exhaust nozzle extending axially downstream of said mixer nozzle, 
 a centre-body axially mounted within and extending axially downstream of the mixer nozzle; 
 a core flow duct defined by the mixer nozzle and the centre-body, the core flow duct having a core exit area; 
 an exhaust duct defined at least in part by the exhaust nozzle downstream of the mixer nozzle, the exhaust duct having an exhaust exit area; and 
 an actuation mechanism; 
 wherein the mixer nozzle comprises a mixer cowl which defines the core exit area and is axially-translatable along the centre axis and wherein the exhaust nozzle comprises an exhaust cowl which defines the exhaust exit area and is either axially-translatable along or angularly-adjustable relative to the centre axis; and 
 wherein the mixer cowl and the exhaust cowl are movable by the actuation mechanism between a first position in which the core exit area and the exhaust exit area are maximum and a second position in which the core exit area and the exhaust exit area are minimum. 
 
     
     
       2. The exhaust nozzle assembly according to  claim 1  where the mixer cowl comprises a mounting portion and a convergent portion converging from the mounting portion. 
     
     
       3. The exhaust nozzle assembly according to  claim 1  wherein the mixer nozzle is a lobed/chute mixer nozzle. 
     
     
       4. The exhaust nozzle assembly according to  claim 1  wherein the centre-body comprises, in an axial downstream direction, a waist portion and a head portion, the head portion comprising in the axial downstream direction, a diverging portion and a converging end portion, the centre-body optionally further comprising an axially upstream convergent portion converging to the waist portion from an axially upstream mounting portion. 
     
     
       5. The exhaust nozzle assembly according to  claim 1  wherein the first position of the mixer cowl is a downstream position with the mixer cowl extended in a downstream direction and the second position of the mixer cowl is an upstream position with the mixer cowl retracted in an upstream direction. 
     
     
       6. The exhaust nozzle assembly according to  claim 1  wherein, in the first position, the core exit area is axially aligned with the centre-body at a portion having a diameter less than the maximum diameter of the centre-body and, in the second position, the core exit area is axially aligned with the centre-body at a portion having a diameter greater than the minimum diameter of the centre-body. 
     
     
       7. The exhaust nozzle assembly according to  claim 6  wherein, in the first position, the core exit area is axially aligned with:
 a) a waist portion of the centre-body; or 
 b) a converging portion upstream of the waist portion. 
 
     
     
       8. The exhaust nozzle assembly according to  claim 6  wherein, in the second position, the core exit area is axially aligned with:
 a) a mounting portion of the centre-body; or 
 b) a converging portion downstream of the mounting portion. 
 
     
     
       9. The exhaust nozzle assembly according to  claim 1  wherein the exhaust cowl comprises a mounting portion and a convergent portion converging from the mounting portion. 
     
     
       10. The exhaust nozzle assembly according to  claim 1  wherein the first position of the exhaust cowl is a downstream position with the exhaust cowl extended in a downstream direction and the second position of the exhaust cowl is an upstream position with the exhaust cowl retracted in an upstream direction. 
     
     
       11. The exhaust nozzle assembly according  claim 1  wherein when the exhaust cowl is in the first position, the exhaust exit area is axially aligned with the centre-body at a first portion having a diameter less than the maximum diameter of the centre-body and, in the second position, the exhaust exit area is axially aligned with the centre-body at a portion having a greater diameter than in the first portion. 
     
     
       12. The exhaust nozzle assembly according to  claim 1  wherein the exhaust cowl comprises a series of circumferentially-arranged cowl petals, each of the cowl petals having a fixed upstream end and a free downstream end wherein the free ends can pivot/hinge about their respective fixed ends to adjust the angle each cowl petal makes relative to the engine axis. 
     
     
       13. The exhaust nozzle assembly according to  claim 1  wherein the actuator mechanism is configured to move/adjust both the mixer cowl and the exhaust cowl in unison between the first and second positions. 
     
     
       14. The exhaust nozzle assembly according to  claim 1  wherein the actuator mechanism comprises a plurality of circumferentially-arranged linear actuators. 
     
     
       15. The exhaust nozzle assembly according to  claim 14  wherein each actuator of the plurality of circumferentially-arranged linear actuators comprises at least one axial linkage. 
     
     
       16. The exhaust nozzle assembly according to  claim 15  wherein the actuation mechanism comprises a radial linkage extending from the at least one axial linkage to the mixer cowl. 
     
     
       17. The exhaust nozzle assembly according to  claim 16 , wherein the actuation mechanism comprises one or more rollers each seated on a respective radially outer cam surface of the exhaust cowl, at least one roller of the one or more rollers being connected directly or indirectly to a respective one of the at least one axial linkage. 
     
     
       18. A gas turbine engine having an exhaust nozzle assembly according to  claim 1 . 
     
     
       19. A supersonic aircraft having a gas turbine engine according to  claim 18 .